Observational evidences on the influences of tropical lower atmospheric day oscillation on the ionospheric equatorial electrojet

Ramkumar, T. K.; Bhavanikumar, Y.; Rao, D. Narayana; Gurubaran, S.; Babu, A. Narendra; Ghosh, Apurna; Rajaram, R. Κ.

doi:10.1016/j.jastp.2005.03.026

Cited by 15 publications

(10 citation statements)

References 43 publications

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“…Pancheva et al () stated the vertical wavelength of UFK waves (3–4 days) above Ascension Island (7.9°S) in 2001/2002 as 40–50 km in agreement with the hypothetical approximation (Forbes, ). Our observation of ~21‐ and ~32‐day oscillations is analogous to the observations of Ramkumar et al () in year 1999. Pancheva et al () observed two discrete crests centered at periods of 5.75 and 6.25 days, whose forte intensifies with altitude for both the sorts of eastward moving Kelvin waves and westward moving Rossby waves.…”

Section: Observations Results and Discussionsupporting

confidence: 92%

Vertical Coupling From the Lower Atmosphere to the Ionosphere: Observations Inferred From Indian MST Radar, GPS Radiosonde, Ionosonde, Magnetometer, OLR (NOAA), and SABER/TIMED Instrument Over Gadanki

et al. 2019

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Simultaneous wind observations from Mesosphere Stratosphere Troposphere (MST) radar collectively with Global Positioning System (GPS) radiosonde over Gadanki, covering altitude range of 3.6–20 km (January–December 2009; 365 days), divulge the propagation of lower atmospheric waves up to the ionosphere. It is combined with temperature data (20–110 km) observed from Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, ionosonde observations, and daily Outgoing Longwave Radiation (OLR) data acquired from the National Ocean and Atmospheric Administration (NOAA; centered around Gadanki [13.5°N, 79.2°E]) for the same time period. Long‐period oscillations with periodicities of ~64, ~32, and ~21 days are witnessed along with the well‐known oscillations of ~16, ~6.4, and ~5.3 days. Most of the long‐period oscillations are dominantly perceived during the summer months (April–June 2009), which can even exist up to September. These long‐period oscillations are found to propagate from lower tropospheric heights up to ionospheric heights with large vertical wavelengths (~300–400 km, in some cases) near to transition zones of atmospheric layers (e.g., tropopause, stratopause, and mesopause). Signatures of vertical coupling of atmosphere through large vertical wavelengths (indicating possible intraseasonal connections) is clearly observed in the equatorial electrojet current and the peak plasma frequencies of ionospheric layers (E and F regions). Noticeable reduction of the wave oscillations in spatial scale with upsurge in spatial damping is evidently visible, in the tropical stratosphere and mesosphere, which can be attributed to stratospheric ozone.

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Section: Observations Results and Discussionsupporting

confidence: 92%

Vertical Coupling From the Lower Atmosphere to the Ionosphere: Observations Inferred From Indian MST Radar, GPS Radiosonde, Ionosonde, Magnetometer, OLR (NOAA), and SABER/TIMED Instrument Over Gadanki

et al. 2019

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“…There is a large collection of papers devoted to the study of oscillations in the ionosphere with periods of the PWs (2-30 days). A small but representative subset of them are the following: Pancheva and Lysenko (1988), Forbes and Leveroni (1992), Pancheva et al (1994), Apostolov et al (1995Apostolov et al ( , 1998, Forbes et al (1997), , Ramkumar et al (2006), Takahashi et al (2006); Lastovicka (2006). Recently, the ionospheric variability in time scales of PWs is studied using regional maps of the total electron content (TEC) derived from GNSS measurements.…”

Section: Introductionmentioning

confidence: 99%

Forcing of the ionosphere from above and below during the Arctic winter of 2005/2006

Mukhtarov

Andonov

Borries³

et al. 2010

Journal of Atmospheric and Solar-Terrestrial Physics

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“…In brief, the EEJ is an enhanced current system with intensity of the order of 200 A/m flowing at about 105 km over the dip equator. More information on EEJ currents and the measurement methods adopted in the present work can be found in the work of Onwumechili [1997] and Ramkumar et al [2006]. They discussed in detail also on how the wind dynamics associated with MLT region can have influences on ionospheric parameters.…”

Section: Introductionmentioning

confidence: 99%

Mesospheric planetary wave signatures in the equatorial electrojet

Ramkumar

Gurubaran

Rajaram³

2009

J. Geophys. Res.

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[1] Using five years (1994)(1995)(1996)(1997)(1998) of simultaneous and collocated measurements of horizontal winds associated with mesosphere and lower thermosphere (MLT) region and geomagnetic field measurements in the Indian geomagnetic dip equatorial region, an extensive experimental study has been made on the influences of mesospheric planetary waves on the equatorial electrojet (EEJ). The winds are measured using medium-frequency (MF) radar (1.98 MHz) located at Tirunelveli. The EEJ strength is determined by measuring the geomagnetic field strength at both the geomagnetic dip and off-dip equatorial stations, Trivandrum and Alibag, India. By noting the simultaneous time evolution of spectral signal (Morlet wavelet analysis) in both the EEJ strength and mesospheric winds at 88 km, it is found that mesospheric planetary waves with periodicities of 2-25 days often do propagate up to the ionospheric dynamo region and have their influences on EEJ strength. Sometimes only one of the parameters shows strong spectral signal in this periodicity range. It is also observed that often the diurnal oscillation in EEJ strength and mesospheric winds exhibits coherent variations in amplitude when the signature of mesospheric planetary-scale oscillations is found in the EEJ strength. Also, it is found that variations in high-energy solar radiations (F10.7 is used as a proxy) can influence the EEJ strength at planetary timescales. This leads to an interesting question. What actually causes the vertical coupling between ionosphere and atmosphere through upward propagating planetary waves to be operative only during some (and not all) of the episodes?

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Observational evidences on the influences of tropical lower atmospheric day oscillation on the ionospheric equatorial electrojet

Cited by 15 publications

References 43 publications

Vertical Coupling From the Lower Atmosphere to the Ionosphere: Observations Inferred From Indian MST Radar, GPS Radiosonde, Ionosonde, Magnetometer, OLR (NOAA), and SABER/TIMED Instrument Over Gadanki

Vertical Coupling From the Lower Atmosphere to the Ionosphere: Observations Inferred From Indian MST Radar, GPS Radiosonde, Ionosonde, Magnetometer, OLR (NOAA), and SABER/TIMED Instrument Over Gadanki

Forcing of the ionosphere from above and below during the Arctic winter of 2005/2006

Mesospheric planetary wave signatures in the equatorial electrojet

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